Conservare gli intonaci storici con gli incentivi statali: due esperienze siciliane

Once traced the historical annotations, the essay presents the analytical activities that supported the restoration project of the facade of palazzo Floridia-Bertini in Ragusa (included into the UNESCO World Heritage List) and villino Arezzo in Ragusa Ibla, and the phases of the restoration sites regarding the techniques of conservation of the stone surfaces and ancient plasters of the two Sicilian architectures. Their restoration has been supported by state incentives, and directed towards the most rigorous conservation of all the elements of the facades: the cleaning operations provided for the removal of the degradation phenomena respecting the material surfaces and natural patinas, and the architectural calcarenite elements have been preserved by applying compatible consolidating products. In both cases, a preliminary thermographic investigation of the plaster highlighted the phenomena of detachment from the wall support and scientifically guided the consolidation with the micro-injections of hydraulic lime and the reintegration of the lacunas. The chemical-physical compatibility with the existing mortars has been verified through laboratory tests on sample and thin slice of stone and plaster, which have highlighted their mineralogical-petrographic characteristics. Some computer simulations guided the final operation of ‘colour veiling’ (calcium carbonate water) in some areas of the facades. The article describes the interventions carried out during the restoration sites and their outcome, recalling the reflections that led to the operational choices. A closing reflection wants to underline the importance of conservation of historical plasters and suggests avoiding the extensive repainting of the facades with colours of pure invention, which alter the perception of the urban scene in the historical districts.